The overall objective of this project is to biochemically characterize the major molecular constituents of cartilage matrix in mice inheriting the cartilage disorder chondrodysplasia (cho/cho). It is anticipated that this homozygous recessive mutant will serve as a model for study of human chondrodystrophy. Specific objectives are aimed at determining the molecular weight of the proteoglycan of mutant hyaline cartilage, its type of sulfation, its rate of synthesis, and its ability to interact with two other important matrix constituents, hyaluronate and collagen. A defect in the interaction between these macromolecules would explain the marked lack of matrix integrity and account for the dramatic aberrant morphology. In vitro experiments have also been designed to examine the biosynthetic rate, type and post-translational modification of collagen synthesized by explanted rib cartilage.